Today's society is becoming increasingly health conscious. In recent years, many new industries have sprung up to promote healthy eating habits and routines of regular exercise. With respect to regular exercise, health club memberships are at an all time high and sales of fitness equipment, both commercial and at-home, are booming.
Numerous studies have been conducted to explore the benefits to the human body of a regular course of daily exercise. A recent article reports that several classic studies have indicated that people who exercise are less likely to die of cardiovascular disease, a leading cause of death in the United States, which is attributable to the fitter person having a lower body weight, lower blood pressure and a better cholesterol profile.
Although the advantages of routine exercising have been well known for many years, the advantages of weight training were first realized only in 1934 when Hoffman, an Olympic weight lifting coach, introduced the concept of weight training for athletes. Weight training is now a common practice used everywhere to train athletes.
In 1945, DeLorme discovered the benefits of weight training in physical medicine and rehabilitation. By the use of his system which utilized the concept of "heavy resistance exercise" he was able to treat a patient with knee anomalies successfully. He also showed that a few repetitions with heavy weight can build up strength and volume in muscles. Since this revelation, many new exercise machines have been developed and constant improvements to those machines are being made.
The human body receives numerous physiological benefits from a properly performed program of daily exercise. For instance, a regular routine of weight training may result in increases in muscle mass, contractile force, flexibility, blood circulation, efficient energy conversion and motor coordination. In addition, regular exercise may have psychological benefits such as an improved sense of well being.
Of course, the results achieved by the individual performing the exercise routine depends on the amount of effort put forth by the individual as well as on certain inherited and unchangeable factors such as genetic make-up, sex and age. Regardless of the human factors, however, an individual must perform a comprehensive exercise program to achieve the best results. For a comprehensive exercise program to be conducted properly, an exercise machine is needed that provides all combinations of exercise protocols, i.e., various combinations of isotonic, isokinetic, isometric or isotonic/isokinetic types of exercises with constant or variable and active or passive force in either one or two directions.
To conduct a comprehensive exercise program, the exerciser needs exercise equipment which can provide a combination of active, passive, uni- and bi-directional resistance. Active resistance is when the resistance to the muscle exists continuously and is independent of motion, whereas, passive resistance provides resistance only when there is motion. In other words, the passive resistance has zero resistance when there is no motion.
Uni-directional resistance generates force in one direction only irrespective of the direction of the user's stroke. Bi-directional resistance, on the other hand, generates force in a direction dependent on the direction of the stroke.
In addition, the exercise protocols widely used in the area of rehabilitation and physical therapy are classified based on the type of resistance a muscle undergoes. The type of change in length that a muscle undergoes determines whether the contraction is termed isometric or static, isotonic or dynamic or isokinetic.
An isometric contraction is one in which the muscle length does not change. An isotonic contraction, contrary to isometric contraction, refers to a contraction in which there is a change in the length of the muscle which undergoes movement about the joint while the resistance is kept constant. In isokinetic contraction, the limb velocity is kept constant throughout the range of motion.
Further, there are classifications on the basis of muscle contractions, namely, concentric or positive and eccentric or negative. The concentric contraction is the controlled shortening of a muscle. The eccentric contraction is the controlled lengthening of a muscle.
To achieve a biomechanically correct conditioning effect, the user of the exercise machine needs a machine that can provide variable resistance in combination with active or passive force and uni- or bi-directional resistance in order to accommodate the varying mechanical leverage of the arms or legs. Furthermore, because a concentric contraction requires four times more oxygen than does an eccentric contraction, the eccentric contraction can assume a larger load and thus, should be loaded with a force greater than that of the eccentric contraction.
In the performance of a complete cycle, power is absorbed during the negative stroke and is generated in the positive stroke. Thus, ideal speed during the negative stroke should be such as to ascertain minimum absorption of power. This refers to zero speed during the negative stroke. However, the exercise should be kept dynamic and therefore, the speed in the negative stroke should be kept as low as possible.
Thus, it would be desirable to incorporate variable resistance producing capabilities into exercise machines, however, to date there are no exercise machines commercially available that have variable resistance in order to accommodate a wide a range of possible exercise protocols.
While exercise is important, exercising correctly is even more important. The term exercising correctly is defined based on the user's age, sex, type of effect desired, the muscle to be exercised, presence of any injury, and other physical features. However, an exerciser of any age or physical condition would benefit from a single exercise machine which could provide: both active and passive, variable resistance as a function of stroke-position; both uni- and bi-directional resistance, i.e., push and pull; a custom programmable resistance profile which is dependent on stroke length; real-time feedback of performance indicators such as work load and calorie spent, etc.; and a low cost, compact, safe and reliable system.
A total of 21 exercise protocols exist which cover all the known combinations of isotonic, isokinetic, isometric and isotonic/isokinetic types of exercises with either a constant force or variable force controlled parameter, an active or passive type of force in a uni-directional or bi-directional direction as shown in Table 1.
TABLE 1 ______________________________________ Type of Controlled Type of Exercise Parameter Force Direction Protocol # ______________________________________ Isotonic Constant Force Active Uni 1 Bi 2 Passive Uni 3 Bi 4 Variable Force Active Uni 5 Bi 6 Passive Uni 7 Bi 8 Isokinetic Constant Force Active Uni 9 Bi 10 Passive Uni 11 Bi 12 Variable Force Active Uni 13 Bi 14 Passive Uni 15 Bi 16 Isometric Constant Force Active Uni 17 Isotonic/ Constant Force/ Active Uni 18 Isokinetic Constant Velocity Bi 19 Passive Uni 20 Bi 21 ______________________________________
It would be desirable for a single exercise machine to be capable of accommodating all of these 21 exercise protocols. Presently, there is no single, multipurpose exercise machine that is capable of performing all the 21 exercise protocols.
Prior art devices, such as taught in U.S. Pat. Nos. 4,930,770 to Baker and 5,015,926 to Casler, are incapable of providing all combinations of isotonic, isokinetic, isometric, or isotonic/isokinetic types of exercises with constant or variable force and active or passive resistance in a uni-directional or bi-directional direction. In particular, a user of the exercise machine taught in either U.S. Pat. No. 4,930,770 to Baker or U.S. Pat. No. 5,015,926 to Casler can only perform exercise protocols in the combination of isotonic, isokinetic, or isotonic/isokinetic exercise protocols with constant and active force in a one direction.
The Casler device uses a constant speed, high torque motor which is mechanically coupled to a dynamic clutch drive. The controlled coupling of the rotary force input to the rotary output is accomplished in the clutch assembly via electromagnetic coil activation of metallic powder particles forming coupling particle chains between the input and the output assemblies. The machine also includes a speed reduction device between the input and the output assemblies and a speed reduction device between the dynamic clutch and the exercise machine. An electric sensor is used to sense speed, motion and torque force of the system output shaft. The sensed information is used to control the coupling torque of the dynamic clutch through a control unit connected to the drive motor and electromagnetic coil of the dynamic clutch which in turn is directed by a microprocessor.
The Baker device is a processor-controlled eccentrically loaded exercise machine. A variable torque motor provides a torque to a magnetic particle torque coupler. The torque coupler is coupled to the user interface device through a gear reducer and a chain and sprocket arrangement. A position sensor and a load cell coupled to the user interface device provide position and force signal to the processor. The processor is capable of providing resisting and powering force which can be varied by position by controlling the motor torque and the torque coupling of the coupler.
Although the Casler and Baker devices are schematically similar to the apparatus of the present invention, the present invention has several features that are distinct from either the Casler or Baker devices. First, Casler uses a constant speed, high torque motor while the apparatus of the present invention uses a reversible, constant torque, variable speed motor. The reversible, constant torque, variable speed motor of the present invention provides more capabilities to an exercise machine to which the apparatus of the present invention is attached. For instance, the constant torque, variable speed motor of the present invention allows an exercise machine to achieve resistance in both a uni-axial direction and a bi-axial direction which is not possible with the Casler device.
Second, Casler's device uses an off-the-shelf magnetic clutch whereas the apparatus of the present invention uses a magnetic particle clutch that has been modified to incorporate a temperature sensor or thermocouple. The incorporation of a temperature sensor or thermocouple into the magnetic particle clutch allows the apparatus of the present invention to be capable of more different exercise protocols with the same efficiency.
Third, the Casler device has a microprocessor-based controller, while the apparatus of the present invention incorporates a microcontroller-based controller which uses a custom developed software that gives the apparatus of the present invention more versatility.
Finally, the Baker device uses a variable torque motor and a standard, unmodified clutch combination which is identical in its capabilities to the Casler device. Thus, Casler and Baker are both capable of accommodating only a certain limited number of exercise protocols, unlike the apparatus of the present invention which is capable of providing all of the 21 protocols shown in Table 1.
With either the Baker or Casler devices, the user could not perform any isometric exercise protocols nor any of the isotonic or isokinetic in combination with any of the following: constant and active force in two directions; constant and passive force in one or two directions; variable and active force in one or two directions; or, variable and passive force in one or two directions.
Furthermore, the user would not be able to perform isotonic/isokinetic exercises with constant force and constant velocity in combination with active, bi-directional resistance nor passive, uni- or bi-directional resistance.
An ideal exercising machine would provide: 1. both active and passive, variable resistance as a function of stroke position; 2. both uni and bi-directional resistance, i.e., push and pull; 3. a custom programmable resistance profile which is stroke length dependent; 4. real-time feedback of performance indicators, e.g., work load or calorie spent; and 5. an apparatus with programmable, variable resistance which is low in cost, compact, safe and reliable.
Most of today's conventional exercise machines can be classified as shown in Table 2, based on the type of device to provide the resistance.
TABLE 2 ______________________________________ Type of Resistance in Exercising Machine Type of exercise machine Type Direction Magnitude ______________________________________ Weight-based Active Uni- Constant direction Cam/spring-based Active Uni- Variable direction Hydraulic/pneumatic- Passive Bi- Constant based direction Magnetic brake-based Passive Bi- Variable direction Cybex Passive Bi- Variable direction Kincom Active, Uni- Variable passive direction Proposed Active, Uni, bi- Variable electromechanical device Passive direction ______________________________________
Weight-based exercise machines satisfy the second requirement of an ideal machine only partially because, as a recent article reports, the inertia causes large fluctuations in the actual resistance as the weight changes speed and direction during the exercise stroke. Thus, weight-based exercise may result in muscles being loaded unevenly since there is no control over the resistance profile.
Cam/spring-based exercise machines are improved versions of weight-based machines since they provide variable resistance with a fixed resistance profile which depends on the cam. However, the cam/spring-based machines only partially satisfy the first, second and third requirements of an ideal machine.
Hydraulic/pneumatic-based exercise machines are passive since the resistance is achieved by forcing a liquid through an orifice. These types of machines provide no resistance when there is no motion and thus, only partially satisfy the second requirement of an ideal machine. While many of the hydraulic/pneumatic machines come with a microprocessor-based monitoring system to satisfy the fourth requirement of an ideal machine, they do not satisfy the fifth requirement of an ideal machine because they incur more than average attendant and maintenance costs.
A pneumatically actuated exercise system which varies the force depending upon the unique force capabilities of the exercising individual has been developed. However, because this system is pneumatically actuated, it suffers from the same inherent drawbacks as the hydraulic/pneumatic machines.
Cybex, a division of Lumex, Inc., has an exercise machine system which uses a dynamometer to obtain the desired force and has an extensive on-line control. The Cybex system has a non-powered mode which allows isokinetic concentric/concentric activity and it accommodates a user's force capability by requiring the user to initiate all movement. Since the clutch disconnects the user from the unit's motor, the Cybex system allows free limb acceleration. The powered mode allows both concentric and eccentric activity as well as continuous passive motion.
However, the Cybex system has certain drawbacks. First, due to the use of the dynamometer, the Cybex system generates force only when there is some motion provided by the user. In other words, it cannot provide active resistance. The Cybex system also is disadvantageous because of its high cost which limits its use to clinical or institutional applications.
The Kincom exercise machine system is used mainly in rehabilitation centers and provides both active and passive resistance. The Kincom system is more versatile than other machines on the market but it still cannot perform all of the at least 21 protocols which the apparatus of the present invention can perform.
Universal Gym Equipment Inc. of Cedar Rapids, Iowa has developed a leg extension machine which is a step forward from the hydraulic/pneumatic systems. The slip torque of a magnetic particle brake is controlled by manipulating the current supplied to the electromagnetic coil that energizes the brake. Although this machine satisfies most of the requirements of an ideal machine, it lacks one important requirement. If such a magnetic brake is used for a bench press machine with this system, the user has to push-up the handle bar and in the reverse direction has to pull-down the bar which is totally different from weight-based bench presses where it is push-up and push-down. This push-up/push-down motion is one of the essential components to receive a biomechanically correct conditioning effect. Hence, Universal's magnetic particle brake device cannot give a multi-purpose exercise machine a biomechanically correct conditioning effect such as is accomplished by the apparatus of the present invention.
It is an object of the present invention to provide a single, multi-purpose exercise machine capable of performing at least 21 possible combinations of isotonic, isokinetic, isometric, or isotonic/isokinetic types of exercise with constant or variable force, active or passive resistance in either one or two directions.
A further object of the present invention is to provide a high performance, microcontroller-based "smart" exercise machine using a magnetic particle clutch to provide the active, passive, uni-, and bi-directional, programmable, variable resistance.
A further object of the present invention is to provide a multi-purpose machine having numerous exercising capabilities, namely, active, passive, uni-, and bi-directional, variable resistance, with custom programmable resistance profile and stroke length to suit a particular individual by providing real-time feedback of work load, progress, and various other performance indicators for monitoring and evaluating the individual's progress.
A further object of the present invention is to provide a low cost, safe, compact, and highly reliable exercising machine.
A further object of the present invention is to replace several existing exercise machines with one compact, multipurpose machine, in place of the traditional weight stack.